Synchrotron radiation issues in the VLHC

Fermilab and other DOE high energy physics laboratories are studying the possibility of a Very Large Hadron Collider (VLHC) for operation in the post-LHC era. The current VLHC design foresees a 2-staged approach, where the second stage (referred to as VLHC-2) has a proton energy up to 100 TeV at a peak luminosity of 2^.10³⁴ cm^-2 sec^-1. The protons are guided through a large 233 km circumference ring with 10 T bending magnets using Nb₃Sn superconductor at 5 K. The synchrotron radiation (SR) power emitted by the beam in such a machine is ~5 W/m/beam. However, other VLHC scenarios with smaller rings and higher luminosity result in SR power levels exceeding this value, reaching 10 or even 20 W/m/beam. Intercepting and removing this power in a cryogenic environment is a major challenge. In this paper a discussion of SR in the VLHC-2, and various approaches to the issue, are presented